Method onAttachCallback

/**
 * Method called when asset attached to the Document.
 * Useful for Asset to add a Script options.
 *
 * @param   Document  $doc  Active document
 *
 * @return void
 *
 * @since   4.0.0
 */
public function onAttachCallback(Document $doc)
{
    // Add core and base uri paths so javascript scripts can use them.
    $doc->addScriptOptions('system.paths', ['root' => Uri::root(true), 'rootFull' => Uri::root(), 'base' => Uri::base(true), 'baseFull' => Uri::base()]);
    HTMLHelper::_('form.csrf');
}